The attention given to Michael Heizer's 'Levitated Mass' at LACMA has many anticipating a masterpiece or a fiasco. But it's not that simple.

On Sunday morning, artist Michael Heizer's eagerly anticipated environmental sculpture, "Levitated Mass," finally opens to the public at the Los Angeles County Museum of Art. At an 11 a.m. ceremony, ribbons will be cut, speeches made, the artist and donors to the $10-million project thanked.

It will also be a moment to rein in expectations. "Levitated Mass" is a good sculpture if not a great one.

Commissioning new art always courts risk. All a museum can do is place its faith in a gifted artist like Heizer and use its institutional clout to help clear the way.

This project encountered an unexpected hurdle. Celebratory hubbub and international media noise accompanied the sculpture's centerpiece — a 340-ton stone megalith — on its remarkable spring journey from a quarry outside Riverside to mid-city L.A.

Huge advance publicity set up a love-it-or-hate-it anticipation for either a masterpiece or a fiasco. But this work is neither. The sober, even solemn finished sculpture at LACMA reminds us that our headlong tendency to divide a world of rich, granular grays into stark black-or-white is its own form of ruin.

"Levitated Mass" is a piece of isolated desert mystery cut into a dense urban setting that's home to nearly 10 million people. A water-hungry lawn north of LACMA's Resnick Pavilion was torn up and replaced by a dry, sun-blasted expanse of decomposed granite. A notched gray channel of polished concrete slices 456 feet across the empty field, set at a slight angle between the pavilion and 6th Street. Like a walk-in version of an alien landscape painting by Surrealist Yves Tanguy, quiet dynamism inflects a decidedly sepulchral scene.

The channel, descending to a depth of 15 feet, is a two-rail pedestal for the huge stone megalith, which is bolted to steel shelves affixed to the center of each side wall. The path slopes gently down, inviting passage, until a visitor stands below ground with the immense boulder spanning the space overhead and blocking out the sun. Surrounding landscapes fall away.

Arrival at the bottom is momentarily disconcerting. After all, how often does one see the underside of a 680,000-pound rock? The bemusement soon dissipates, though, replaced by simple curiosity about the construction's elaborate engineering.

The pyramidal stone has been cut across the bottom to fit those heavily ribbed steel shelves. Thick bolts anchor it in place, conforming to essential demands for earthquake safety. Slits at each side of the concrete floor provide drainage for inevitable rains, as do drains hidden beneath the surrounding decomposed-granite field.

Returning to the surface, other details emerge. The long channel is encircled by a lozenge-shaped line of Cor-Ten steel, embedded in the earth and rusting to a velvety brown. Decomposed granite, sloping gently toward the slot, seems like a forecast of the megalith's slowly decaying future, reaching forward to its destiny thousands of years hence. The surrounding cityscape suddenly appears vain and fragile, the sculpture's most affecting feature.

Sophisticated industrial technology fuses abstract 1960s Minimalist sculpture with an ancient monumental form. (Heizer's late father, a noted anthropologist and archaeologist, was collaborating on a book about the transport of massive stones in antiquity when he died in 1979.)

Megaliths are large stone markers, used by diverse civilizations over millenniums to create ritual spaces, mark geographic territory or identify a grave site.

Look at Caspar David Friedrich's painting "A Walk at Dusk," circa 1830-35, a bleak and wintry little masterpiece at theJ. Paul Getty Museum. The crepuscular landscape shows a man contemplating an ancient megalithic tomb. With its oblique message of mortality, nature's eternal cycles are encoded in a misty crescent moon.

Heizer, 67, conceived the work 43 years ago. It was an early manifestation of Land art, an international movement among artists to work directly with the landscape as material, rather than representing it in paintings or depositing discreet sculptures on it. (Currently a good survey of the movement, "Ends of the Earth: Land Art to 1974," is at the Museum of Contemporary Art, although the reclusive Heizer declined to participate.) The specific site of "Levitated Mass" today resonates in ways he couldn't have considered then.

The brooding sculptural ensemble marks time both cultural and geological. Adjacent to an urban art museum, repository for the relics of civilizations gone by, it's also next to the La Brea Tar Pits, resting place for prehistoric bones sunken into the primordial goo. Unavoidably, it calls for contemplation of our transient place in the larger scheme of things.

It will also surely beckon skateboarders eager to navigate its sloping ramp. Posted museum guards will likely thwart that urge.